linux-kernel - Re: [PATCH v3] of: reserved_mem: Restructure call site for dma_contiguous_early

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Message-ID: <20250730224132.GA1822233-robh@kernel.org>
Date: Wed, 30 Jul 2025 17:41:42 -0500
From: Rob Herring <robh@...nel.org>
To: Oreoluwa Babatunde <oreoluwa.babatunde@....qualcomm.com>
Cc: m.szyprowski@...sung.com, robin.murphy@....com, saravanak@...gle.com,
	quic_obabatun@...cinc.com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
	william.zhang@...adcom.com, kernel@....qualcomm.com,
	will@...nel.org, djakov@...nel.org
Subject: Re: [PATCH v3] of: reserved_mem: Restructure call site for
 dma_contiguous_early_fixup()

On Tue, Jul 29, 2025 at 05:29:56PM -0700, Oreoluwa Babatunde wrote:
> Restructure the call site for dma_contiguous_early_fixup() to
> where the reserved_mem nodes are being parsed from the DT so that
> dma_mmu_remap[] is populated before dma_contiguous_remap() is called.
> 
> Fixes: 8a6e02d0c00e ("of: reserved_mem: Restructure how the reserved memory regions are processed")
> Signed-off-by: Oreoluwa Babatunde <oreoluwa.babatunde@....qualcomm.com>
> Tested-by: William Zhang <william.zhang@...adcom.com>
> ---
> v3: Wrap the call to dma_contiguous_early_fixup() with a check for
>     CONFIG_DMA_CMA to fix compile error seen on x86. The __weak function
>     definition introduced in v2 was not sufficient to prevent the issue,
>     so remove that as well.
>     Also add Tested-by tag from William Zhang.
> 
> v2: Add a check for the "reusable" property to narrow things down to
>     only cma regions.
>     Also add __weak function definition for dma_contiguous_early_fixup()
>     to avoid compile errors on architectures that do not define the
>     function.
> 
>  drivers/of/of_reserved_mem.c | 20 ++++++++++++++++----
>  kernel/dma/contiguous.c      |  2 --
>  2 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 77016c0cc296..cfffecb91c3a 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -25,6 +25,7 @@
>  #include <linux/memblock.h>
>  #include <linux/kmemleak.h>
>  #include <linux/cma.h>
> +#include <linux/dma-map-ops.h>
>  
>  #include "of_private.h"
>  
> @@ -175,13 +176,19 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
>  		base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>  		size = dt_mem_next_cell(dt_root_size_cells, &prop);
>  
> -		if (size &&
> -		    early_init_dt_reserve_memory(base, size, nomap) == 0)
> +		if (size && early_init_dt_reserve_memory(base, size, nomap) == 0) {
> +			/* Architecture specific contiguous memory fixup. */
> +#ifdef CONFIG_DMA_CMA
> +			if (of_flat_dt_is_compatible(node, "shared-dma-pool") &&
> +			    of_get_flat_dt_prop(node, "reusable", NULL))
> +				dma_contiguous_early_fixup(base, size);
> +#endif

Add a static inline for dma_contiguous_early_fixup() instead of having 
an #ifdef.

>  			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %lu MiB\n",
>  				uname, &base, (unsigned long)(size / SZ_1M));
> -		else
> +		} else {
>  			pr_err("Reserved memory: failed to reserve memory for node '%s': base %pa, size %lu MiB\n",
>  			       uname, &base, (unsigned long)(size / SZ_1M));
> +		}
>  
>  		len -= t_len;
>  	}
> @@ -472,7 +479,12 @@ static int __init __reserved_mem_alloc_size(unsigned long node, const char *unam
>  		       uname, (unsigned long)(size / SZ_1M));
>  		return -ENOMEM;
>  	}
> -
> +#ifdef CONFIG_DMA_CMA
> +	/* Architecture specific contiguous memory fixup. */
> +	if (of_flat_dt_is_compatible(node, "shared-dma-pool") &&
> +	    of_get_flat_dt_prop(node, "reusable", NULL))
> +		dma_contiguous_early_fixup(base, size);
> +#endif
>  	/* Save region in the reserved_mem array */
>  	fdt_reserved_mem_save_node(node, uname, base, size);
>  	return 0;
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 67af8a55185d..d9b9dcba6ff7 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -483,8 +483,6 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
>  		pr_err("Reserved memory: unable to setup CMA region\n");
>  		return err;
>  	}
> -	/* Architecture specific contiguous memory fixup. */
> -	dma_contiguous_early_fixup(rmem->base, rmem->size);
>  
>  	if (default_cma)
>  		dma_contiguous_default_area = cma;
> -- 
> 2.34.1
>